Reginaia rotulata - (Wright, 1899)
Round Ebonyshell
Synonym(s): Fusconaia rotulata (Wright, 1899) ;Obovaria rotulata (Wright, 1899)
Taxonomic Status: Accepted
Related ITIS Name(s): Obovaria rotulata (Wright, 1899) (TSN 80178)
Unique Identifier: ELEMENT_GLOBAL.2.116158
Element Code: IMBIV31040
Informal Taxonomy: Animals, Invertebrates - Mollusks - Freshwater Mussels
 
Kingdom Phylum Class Order Family Genus
Animalia Mollusca Bivalvia Unionoida Unionidae Reginaia
Genus Size: B - Very small genus (2-5 species)
Check this box to expand all report sections:
Concept Reference
Help
Concept Reference: Turgeon, D.D., J.F. Quinn, Jr., A.E. Bogan, E.V. Coan, F.G. Hochberg, W.G. Lyons, P.M. Mikkelsen, R.J. Neves, C.F.E. Roper, G. Rosenberg, B. Roth, A. Scheltema, F.G. Thompson, M. Vecchione, and J.D. Williams. 1998. Common and scientific names of aquatic invertebrates from the United States and Canada: Mollusks. 2nd Edition. American Fisheries Society Special Publication 26, Bethesda, Maryland: 526 pp.
Concept Reference Code: B98TUR01EHUS
Name Used in Concept Reference: Obovaria rotulata
Taxonomic Comments: Included in Turgeon et al. (1998) as Obovaria rotulata but later reassigned to Reginaia (Campbell and Lydeard 2012). This reassignment was accepted by Williams et al. (2017). Placed in the genus Fusconaia by Williams and Butler (1994) and Williams et al. (2008).
Conservation Status
Help

NatureServe Status

Global Status: G1
Global Status Last Reviewed: 14Jan2014
Global Status Last Changed: 28Jul1998
Rounded Global Status: G1 - Critically Imperiled
Reasons: This species is endemic to a small stretch of only one river, one of the most restricted ranges of all North American unionids. Further, this river is one of the most degraded in Florida, although status may be improving. Declining populations, limited distribution, restricted habitat, possible decreasing numbers of extant sites, questionable viability of extant populations, increased watershed siltation, and bank erosion contributing to deteriorating habitat and water quality all threaten the species with extinction.
Nation: United States
National Status: N1 (03Feb1997)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Alabama (S1), Florida (S1)

Other Statuses

U.S. Endangered Species Act (USESA): LE: Listed endangered (10Oct2012)
U.S. Fish & Wildlife Service Lead Region: R4 - Southeast
IUCN Red List Category: EN - Endangered
American Fisheries Society Status: Endangered (01Jan1993)

NatureServe Global Conservation Status Factors

Range Extent: <100 square km (less than about 40 square miles)
Range Extent Comments: This is an Apalachicolan region endemic form restricted to the Escambia/Conecuh drainage (same river, but the name changes across the state boundary) in Florida and Alabama, where it is known from east Brewton, Escambia County, Alabama (Conecuh River), downstream for a distance of approximately 75 river km. No occurrences are known for tributaries (Williams and Butler, 1994; Johnson, 1967; Williams et al., 2008). Due to recent survey data the known historical range for the round ebonyshell was expanded (based on shell material only) to include the Conecuh River from the junction with the Sepulga River, Escambia County, Alabama, downstream in the Escambia River to Bluff Springs, Escambia and Santa Rosa counties, Florida (fide Williams et al., 2008), for a total historic range of approximately 95 km (59 river miles) (USFWS, 2003; Williams et al., 2000).

Area of Occupancy: 6-25 4-km2 grid cells
Area of Occupancy Comments: This species has one of most restricted ranges known for a North American unionid. The current range of live round ebonyshell individuals is restricted to ca. 40-75 river km. Linear occupancy is 40-200 km.

Number of Occurrences: 1 - 5
Number of Occurrences Comments: The current range of live round ebonyshell individuals is restricted to <100 km (43 according to Johnson [1967]. Only 3 of 9 historic locations contain living individuals, thereby indicating a 67% decline in the number of sites known to support this species. In Alabama it only remains in the Conecuh River (same as Escambia River), where it is extremely rare (Williams et al., 2008).

Population Size: 50 - 1000 individuals
Population Size Comments: Apparently this species is extremely uncommon (at least historically), but no known recent efforts have been expended there, or at most of the other known sites. It was possibly never abundant, as some historic collections are fairly small.

Number of Occurrences with Good Viability/Integrity: None (zero)
Viability/Integrity Comments: Round ebonyshell population levels within the Escambia River drainage are extremely low. On average, only 2 live individuals were found at the remaining 3 sites (Williams et al. unpublished data). It is unknown if these remaining populations are capable of reproduction and recruitment (see USFWS, 2003).

Overall Threat Impact: Very high - high
Overall Threat Impact Comments: Habitat modification is the most significant threat. The stream and river habitats are vulnerable to habitat modification, sedimentation, and water quality degradation from a number of activities. Highway and reservoir construction, improper logging practices, agricultural runoff, housing developments, pipeline crossings, and livestock grazing often result in physical disturbance of stream substrates or the riparian zone, and/or changes in water quality, temperature, or flow. Sedimentation can cause direct mortality of mussels by deposition and suffocation (Ellis, 1936; Brim Box and Mossa, 1999) and can eliminate or reduce the recruitment of juvenile mussels (Negus, 1966; Brim Box and Mossa, 1999). Suspended sediment can also interfere with feeding activity of mussels (Dennis, 1984). Many of the confirmed extant populations of this species are in the vicinity of highway and unpaved road crossings due to ease of access for surveyors. Highway and bridge construction and widening could affect populations of these species unless appropriate precautions are implemented during construction to reduce erosion and sedimentation, and maintain water quality standards. The construction of reservoirs and the associated habitat changes (e.g., changes of sediments, flow, water temperature, dissolved oxygen) can directly impact mussel populations (Neves et al., 1997). Nutrients, usually phosphorus and nitrogen, may emanate from agricultural fields, residential lawns, livestock feedlots, poultry houses, and leaking septic tanks in levels that result in eutrophication and reduced oxygen levels in small streams. Other factors include (1) over-utilization for commercial, recreational, scientific, or educational purposes (note: species is not commercially valuable nor are the streams and rivers it inhabits subject to harvesting activities for commercial mussel species), (2) disease or predation (poorly known but may contribute to the further decline of these species due to their restricted distributions and low numbers associated with extant populations), (3) the inadequacy of existing regulatory mechanisms (note: less success in dealing with non-point source pollution impacts, particularly sediments, to small stream drainages), (4) catastrophic events (populations are generally small and geographically isolated; the round ebonyshell is vulnerable to catastrophic events because of low population numbers known from 3 sites), (5) host fish loss or decline (note host not known), (6) populations below effective population size to maintain long term viability (some populations below required population size to maintain long-term genetic viability), (7) invasive species (Asiatic clam, zebra mussel, black carp) (see USFWS, 2003).

Short-term Trend: Decline of 50-70%
Short-term Trend Comments: Recent status surveys indicated that this species has experienced severe range reductions and occurs in low abundance within its limited range. Only 3 of 9 historic locations contain living individuals, thereby indicating a 67% decline in the number of sites known to support this species (see USFWS, 2003).

Long-term Trend: Decline of 50-70%

Intrinsic Vulnerability: Highly to moderately vulnerable.
Intrinsic Vulnerability Comments: Freshwater mussels are inherently vulnerable to threats from siltation, pollution, eutrophication, channelization, impoundment, collection, drought and water withdrawal, competiton from invasive non-native mussels, and changes to larval host fish populations.

Environmental Specificity: Very narrow to moderate.

Other NatureServe Conservation Status Information

Inventory Needs: Determine status of extant populations, resurvey historic sites, and search for new ones by conducting intensive surveys throughout the entire Conecuh/Escambia River mainstem from river falls downstream to tidal influence. Inventory potential habitat for future reintroduction of cultured stock/tranplants.

Protection Needs: Maintain high water and benthic habitat (substrate) qualities, as well as adequate flow regimes, throughout the Escambia/Conecuh River system. This may be partially accomplished via establishment of buffers and streamside management zones for all agricultural, silvicultural, mining, and developmental activities; protection of floodplain forests and adjoining upland habitat is paramount. Best management practices to follow include employing forestry practices that cause minimal soil erosion; preventing access of livestock to natural surface waters and drains; situating roads at least 0.25 mi. (0.4 km) from heads of all tributaries, even more on steep slopes; using silt fencing and vegetation to control runoff and siltation at all stream crossings, especially during construction and maintenance; using and maintaining sewer systems rather than septic tanks and stream-dumping for management of wastewater; and avoiding use of agricultural pesticides on porous soils near streams. Prevent damming, dredging, and pollution throughout drainages, but especially near recorded sites. Remove existing dams, but with great care to limit downstream sedimentation. Limit withdrawal of surface and subterranean waters as necessary to maintain normal stream flows, especially during drought. Prevent or limit establishment of invasive species (including zebra mussel, Dreissena polymorpha) to the extent possible. Where appropriate, protect populations through acquisitions and easements over streamside lands by working with government agencies and conservation organizations. See also U.S. Fish and Wildlife Service (2003).

Distribution
Help
Global Range: (<100 square km (less than about 40 square miles)) This is an Apalachicolan region endemic form restricted to the Escambia/Conecuh drainage (same river, but the name changes across the state boundary) in Florida and Alabama, where it is known from east Brewton, Escambia County, Alabama (Conecuh River), downstream for a distance of approximately 75 river km. No occurrences are known for tributaries (Williams and Butler, 1994; Johnson, 1967; Williams et al., 2008). Due to recent survey data the known historical range for the round ebonyshell was expanded (based on shell material only) to include the Conecuh River from the junction with the Sepulga River, Escambia County, Alabama, downstream in the Escambia River to Bluff Springs, Escambia and Santa Rosa counties, Florida (fide Williams et al., 2008), for a total historic range of approximately 95 km (59 river miles) (USFWS, 2003; Williams et al., 2000).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
Endemism: endemic to a single nation

U.S. & Canada State/Province Distribution
United States AL, FL

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
AL Escambia (01053)*
FL Escambia (12033), Santa Rosa (12113)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
03 Lower Conecuh (03140304)+, Escambia (03140305)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
U.S. Distribution by Watershed (based on multiple information sources) Help
Ecology & Life History
Help
Basic Description: A medium-sized circular, dark, thick-shelled freshwater mussel.
General Description: The round ebonyshell is a small to medium-sized mussel that attains a maximum length of 61 mm. The shell is thick, heavy, inflated, and circular in outline. There is no posterior ridge, but often two slight folds are present. The periostracum is dark brown to black. Internally, the interdentum is moderately broad, with straight to slightly curved lateral teeth. The umbo cavity is deep and wide and nacre is iridescent white (Williams et al., 2000). See also Johnson (1967) and Williams and Butler (1994).
Diagnostic Characteristics: Circular outline, heavy shelled, smooth black periostracum, with a deep umbonal pocket (unlike the shallow pocket typical of Obovaria spp.).
Reproduction Comments: Presumably tachytictic (short-term brooder), similar to Fusconaia ebena and other congeners. The glochidial host is not known.
Ecology Comments: Apparently the eastern Gulf drainage counterpart of Fusconaia ebena (Lea, 1831).
Habitat Type: Freshwater
Non-Migrant: Y
Locally Migrant: N
Long Distance Migrant: N
Mobility and Migration Comments: Greatest potential during glochidial stage on fish. Adults of this species are essentially sessile however some passive movement downstream may occur during high flows.
Riverine Habitat(s): BIG RIVER, Low gradient, Riffle
Special Habitat Factors: Benthic
Habitat Comments: Ecological data regarding the round ebonyshell are sparse at best. This animal only occurs in one main river channel, with moderate current over sand and gravel substrate (Williams and Butler, 1994). "In muddy sand and sand in moderate current" (Heard, 1979). "Confined to the main channel of the Escambia [and its extension in Alabama, the Conecuh] River[s] in areas with moderate current and a mixture of sand and gravel substrates" (Williams and Butler, 1994).
Adult Food Habits: Detritivore
Immature Food Habits: Parasitic
Food Comments: Presumably fine particulate organic matter, primarily detritus, and/or zooplankton, and/or phytoplankton (Fuller, 1974). Larvae (glochidia) of freshwater mussels generally are parasitic on fish and there may be a specificity among some species.
Length: 6.1 centimeters
Economic Attributes Not yet assessed
Help
Management Summary
Help
Stewardship Overview: Conservation activities have been limited to working with landowners in west Alabama and south Florida to limit the effects of agricultural practices on populations. This species has probably been negatively affected greatest by poor land use practices resulting in habitat destruction and leading to decline and imperilment. It has been listed as a USFWS candidate species in the U.S. (USFWS, 2003).

Biological Research Needs: Develop propagation techniques; determine life history, reproductive biology, fecundity, viability of extant populations; identify host fish, its requirements, population status, microhabitat requirements, and its sensitivity to siltation, excessive nutrients, and pollutants.
Population/Occurrence Delineation
Help
Group Name: Freshwater Mussels

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on some evidence of historical or current presence of single or multiple specimens, including live specimens or recently dead shells (i.e., soft tissue still attached and/or nacre still glossy and iridescent without signs of external weathering or staining), at a given location with potentially recurring existence. Weathered shells constitute a historic occurrence. Evidence is derived from reliable published observation or collection data; unpublished, though documented (i.e. government or agency reports, web sites, etc.) observation or collection data; or museum specimen information.
Mapping Guidance: Based on the separation distances outlined herein, for freshwater mussels in STANDING WATER (or backwater areas of flowing water such as oxbows and sloughs), all standing water bodies with either (1) greater than 2 km linear distance of unsuitable habitat between (i.e. lotic connections), or (2) more than 10 km of apparently unoccupied though suitable habitat (including lentic shoreline, linear distance across water bodies, and lentic water bodies with proper lotic connections), are considered separate element occurrences. Only the largest standing water bodies (with 20 km linear shoreline or greater) may have greater than one element occurrence within each. Multiple collection or observation locations in one lake, for example, would only constitute multiple occurrences in the largest lakes, and only then if there was some likelihood that unsurveyed areas between collections did not contain the element.

For freshwater mussels in FLOWING WATER conditions, occurrences are separated by a distance of more than 2 stream km of unsuitable habitat, or a distance of more than 10 stream km of apparently unoccupied though suitable habitat. Standing water between occurrences is considered suitable habitat when calculating separation distance for flowing water mussel species unless dispersal barriers (see Separation Barriers) are in place.

Several mussel species in North America occur in both standing and flowing water (see Specs Notes). Calculation of separation distance and determination of separation barriers for these taxa should take into account the environment in which the element was collected. Juvenile mussels do not follow this pattern and juveniles are typically missed by most standard sampling methods (Hastie and Cosgrove, 2002; Neves and Widlak, 1987), therefore juvenile movement is not considered when calculating separation distance.

Separation Barriers: Separation barriers within standing water bodies are based solely on separation distance (see Separation Distance-suitable, below). Separation barriers between standing water bodies and within flowing water systems include lack of lotic connections, natural barriers such as upland habitat, absence of appropriate species specific fish hosts, water depth greater than 10 meters (Cvancara, 1972; Moyle and Bacon, 1969) or anthropogenic barriers to water flow such as dams or other impoundments and high waterfalls.
Separation Distance for Unsuitable Habitat: 2 km
Separation Distance for Suitable Habitat: 10 km
Alternate Separation Procedure: None
Separation Justification: Adult freshwater mussels are largely sedentary spending their entire lives very near to the place where they first successfully settled (Coker et al., 1921; Watters, 1992). Strayer (1999) demonstrated in field trials that mussels in streams occur chiefly in flow refuges, or relatively stable areas that displayed little movement of particles during flood events. Flow refuges conceivably allow relatively immobile mussels to remain in the same general location throughout their entire lives. Movement occurs with the impetus of some stimulus (nearby water disturbance, physical removal from the water such as during collection, exposure conditions during low water, seasonal temperature change or associated diurnal cycles) and during spawning. Movement is confined to either vertical movement burrowing deeper into sediments though rarely completely beneath the surface, or horizontal movement in a distinct path often away from the area of stimulus. Vertical movement is generally seasonal with rapid descent into the sediment in autumn and gradual reappearance at the surface during spring (Amyot and Downing, 1991; 1997). Horizontal movement is generally on the order of a few meters at most and is associated with day length and during times of spawning (Amyot and Downing, 1997). Such locomotion plays little, if any, part in the distribution of freshwater mussels as these limited movements are not dispersal mechanisms. Dispersal patterns are largely speculative but have been attributed to stream size and surface geology (Strayer, 1983; Strayer and Ralley, 1993; van der Schalie, 1938), utilization of flow refuges during flood stages (Strayer, 1999), and patterns of host fish distribution during spawning periods (Haag and Warren, 1998; Watters, 1992). Lee and DeAngelis (1997) modeled the dispersal of freshwater into unoccupied habitats as a traveling wave front with a velocity ranging from 0.87 to 2.47 km/year (depending on mussel life span) with increase in glochidial attachment rate to fish having no effect on wave velocity.

Nearly all mussels require a host or hosts during the parasitic larval portion of their life cycle. Hosts are usually fish, but a few exceptional species utilize amphibians as hosts (Van Snik Gray et al., 2002; Howard, 1915) or may metamorphose without a host (Allen, 1924; Barfield et al., 1998; Lefevre and Curtis, 1911; 1912). Haag and Warren (1998) found that densities of host generalist mussels (using a variety of hosts from many different families) and displaying host specialists (using a small number of hosts usually in the same family but mussel females have behavioral modifications to attract hosts to the gravid female) were independent of the densities of their hosts. Densities of non-displaying host specialist mussels (using a small number of hosts usually in the same family but without host-attracting behavior) were correlated positively with densities of their hosts. Upstream dispersal of host fish for non-displaying host specialist mussels could, theoretically, transport mussel larvae (glochidia) over long distances through unsuitable habitat, but it is unlikely that this occurs very often. D. Strayer (personal communication) suggested a distance of at least 10 km, but a greater distance between occurrences may be necessary to constitute genetic separation of populations. As such, separation distance is based on a set, though arbitrary, distance between two known points of occurrence.

Date: 18Oct2004
Author: Cordeiro, J.
Notes: Contact Jay Cordeiro (jay_cordeiro@natureserve.org) for a complete list of freshwater mussel taxa sorted by flow regime.
Population/Occurrence Viability
Help
Justification: Use the Generic Element Occurrence Rank Specifications (2008).
Key for Ranking Species Element Occurrences Using the Generic Approach (2008).
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
Help
Authors/Contributors
Help
NatureServe Conservation Status Factors Edition Date: 08Jan2014
NatureServe Conservation Status Factors Author: Jackson, D. R. (2014); Cordeiro, J. (2009); Butler, R.S., B.J. Downes, and D.R. Jackson (1998)
Management Information Edition Date: 08Mar2005
Management Information Edition Author: Cordeiro, J.
Element Ecology & Life History Edition Date: 26Jan2007
Element Ecology & Life History Author(s): Cordeiro, J.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
Help
  • Athearn, H.D. 1998. Additional records and notes on the unionid fauna of the Gulf Drainage of Alabama, Georgia, and Florida. Occasional Papers on Mollusks, 5(76): 465-467.

  • Brim Box, J. and J. Mossa. 1999. Sediment, land use, and freshwater mussels: prospects and problems. Journal of the North American Benthological Society, 18(1): 99-117.

  • Campbell, D. and P. Harris. 2006. Report on molecular systematics of poorly-known freshwater mollusks of Alabama. Report to the Alabama Department of Conservation and Natural Resources, Montgomery, Alabama. 34 pp.

  • Campbell, D.C. and C. Lydeard. 2012. The genera of the Pleurobemini (Bivalvia: Unionidae: Ambleminae). American Malacological Bulletin 30(1):19-38.

  • Dennis, S.D. 1984. Distributional analysis of the freshwater mussel fauna of the Tennessee River system, with special reference to possible limiting effects of siltation. Ph.D. Thesis. Virginia Polytechnic Institute and State University, Blacksburg, Virginia. 247 pp.

  • Deyrup, M. and R. Franz. 1994. Rare and Endangered Biota of Florida, Volume IV. Invertebrates. University Press of Florida: Gainesville, Florida. 798 pp.

  • Deyrup, M., and R. Franz. 1994. Rare and Endangered Biota of Florida, Volume IV: Invertebrates. University Press of Florida, Gainesville. 798 pp.

  • Ellis, M.M. 1936. Erosion silt as a factor in aquatic environments. Ecology, 17: 29-42.

  • Fuller, S.L.H. 1974. Chapter 8: Clams and mussels (Mollusca: Bivalvia). Pages 215-273 in: C.W. Hart, Jr. and S.L.H. Fuller (eds.) Pollution Ecology of Freshwater Invertebrates. Academic Press: New York. 389 pp.

  • Heard, W.H. 1979. Identification manual of the fresh water clams of Florida. State of Florida, Department of Environmental Regulation, Technical Series, 4(2): 1-82.

  • Howard, A.D. 1915. Some exceptional cases of breeding among the Unionidae. The Nautilus 29:4-11.

  • Johnson, R.I. 1967a. Additions to the Unionid fauna of the Gulf Drainage of Alabama, Georgia and Florida (Mollusca: Bivalvia). Breviora 270: 1-21.

  • Johnson, R.I. 1967b. Carunculina pulla (Conrad), an overlooked Atlantic drainage unionid. The Nautilus 80(4): 127-131.

  • Johnson, R.I. 1970. The systematics and zoogeography of the Unionidae (Mollusca: Bivalvia) of the southern Atlantic Slope Region. Bulletin of the Museum of Comparative Zoology 140(6):263-449. 140(6):263-449.

  • Johnson, R.I. 1970a. The systematics and zoogeography of the Unionidae (Mollusca: Bivalvia) of the southern Atlantic slope region. Bulletin of the Museum of Comparative Zoology, Harvard University 140(6): 263-449.

  • Lefevre, G. and W.T. Curtis. 1912. Studies on the reproduction and artificial propogation of fresh-water mussels. Bulletin of the Bureau of Fisheries 30:102-201.

  • Lydeard, C., R. Minton, and J.D. Williams. 2000. Prodigious polyphyly in imperiled freshwater pearly-mussels (Bivalvia: Unionidae): a phylogenetic test of species and generic designations. Pages 145-158 In E.M. Harper, J. D. Taylor, and J. A. Crame (eds.) The Evolutionary Biology of the Bivalvia. Geological Society of London, Special Publications 177.

  • Mirarchi, R.E., J.T. Garner, M.F. Mettee, and P.E. O'Neil. 2004b. Alabama wildlife. Volume 2. Imperiled aquatic mollusks and fishes. University of Alabama Press, Tuscaloosa, Alabama. xii + 255 pp.

  • Moyle, P. and J. Bacon. 1969. Distribution and abundance of molluscs in a fresh water environment. Journal of the Minnesota Academy of Science 35(2/3):82-85.

  • Negus, C.L. 1966. A quantitative study of growth and production of unionid mussels in the River Thames at Reading. Journal of Animal Ecology, 35: 513-532.

  • Neves, R.J., A.E. Bogan, J.D. Williams, S.A. Ahlstedt, and P.W. Hartfield. 1997. Status of aquatic mollusks in the southeastern United States: a downward spiral of diversity. Pages 43-85 in G.W. Benz and D.E. Collins (eds.) Aquatic Fauna in Peril: the Southeastern Perspective. Special Publication 1, Southeast Aquatic Research Institute, Chattanooga, Tennessee.

  • Strayer, D. 1983. The effects of surface geology and stream size on freshwater mussel (Bivalvia, Unionidae) distribution in southeastern Michigan, U.S.A. Freshwater Biology 13:253-264.

  • Strayer, D.L. 1999a. Use of flow refuges by unionid mussels in rivers. Journal of the North American Benthological Society 18(4):468-476.

  • Strayer, D.L. and J. Ralley. 1993. Microhabitat use by an assemblage of stream-dwelling unionaceans (Bivalvia) including two rare species of Alasmidonta. Journal of the North American Benthological Society 12(3):247-258.

  • Turgeon, D.D., J.F. Quinn, Jr., A.E. Bogan, E.V. Coan, F.G. Hochberg, W.G. Lyons, P.M. Mikkelsen, R.J. Neves, C.F.E. Roper, G. Rosenberg, B. Roth, A. Scheltema, F.G. Thompson, M. Vecchione, and J.D. Williams. 1998. Common and scientific names of aquatic invertebrates from the United States and Canada: Mollusks. 2nd Edition. American Fisheries Society Special Publication 26, Bethesda, Maryland: 526 pp.

  • U.S. Fish and Wildlife Service. 2011i. Endangered and threatened wildlife and plants; endangered status for the Alabama pearlshell, round ebonyshell, southern sandshell, southern kidneyshell, and choctaw bean, and threatened status for the tapered pigtoe, narrow pigtoe, and fuzzy pigtoe; with critical habitat. Federal Register 76(192):61482-61529.

  • U.S. Fish and Wildlife Service. 2012f. Endangered and threatened wildlife and plants; endangered species status for the Alabama pearlshell, round ebonyshell, southern kidneyshell, and choctaw bean, and threatened species status for the tapered pigtoe, narrow pigtoe, southern sandshell, and fuzzy pigtoe; and designation of critical habitat; final rule. Federal Register 77(196):61664-61719.

  • Van der Schalie, H. 1938a. The naiad fauna of the Huron River in southeastern Michigan. Miscellaneous Publication of the Museum of Zoology, University of Michigan 40:7-78.

  • Watters, G.T. 1992a. Unionids, fishes, and the species-area curve. Journal of Biogeography 19:481-490.

  • Williams, J. D., A. E. Bogan, and J. T Garner. 2008. Freshwater mussels of Alabama & the Mobile Basin in Georgia, Mississippi, & Tennessee. University of Alabama Press, Tuscaloosa, Alabama. 908 pages.

  • Williams, J. D., A. E. Bogan, and J. T. Garner. 2008. Freshwater Mussels of Alabama and the Mobile Basin in Georgia, Mississippi and Tennessee. University of Alabama Press, Tuscaloosa, Alabama. 908 pp.

  • Williams, J. D., A. E.Bogan, R. S. Butler, K. S.Cummings, J. T. Garner, J. L. Harris, N. A. Johnson, and G. T. Watters. 2017. A revised list of the freshwater mussels (mollusca: bivalvia: unionida) of the United States and Canada. Freshwater Mollusk Biology and Conservation 20:33-58.

  • Williams, J. D., M. L. Warren, Jr., K. S. Cummings, J. L. Harris, and R. J. Neves. 1992. Conservation status of freshwater mussels of the United States and Canada. Fisheries 18(9):6-22.

  • Williams, J. D., R. S. Butler, G. L. Warren, and N. A. Johnson.  2014.  Freshwater Mussels of Florida.  University of Alabama Press, Tuscaloosa.  498 pp.

  • Williams, J. D., R. S. Butler, G. L. Warren, and N. A. Johnson.  2014a.  Freshwater Mussels of Florida.  University of Alabama Press, Tuscaloosa, Alabama. 498 pp.

  • Williams, J. D., and A. Fradkin. 1999. Fusconaia apalchicola, a new species of freshwater mussel (Bivalvia: Unionidae) from precolumbian archaeological sites in the Apalachicola basin of Alabama, Florida, and Georgia. Tulane Stud. Zool. Bot. 31:51-62.

  • Williams, J.D. and R.S. Butler. 1994. Class Bivalvia, Order Unionoida, freshwater bivalves. Pages 53-128, 740-742 in M. Deyrup and R. Frantz (eds.) Rare and Endangered Biota of Florida. Volume 4. Invertebrates. University Press of Florida, Gainesville, Florida. 798 pp.

  • Williams, J.D., H.N. Blalock, A. Benson, and D.N. Shelton. 2000. Distribution of the freshwater mussel fauna (Bivalvia: Margaritiferidae and Unionidae) in the Escambia and Yellow river drainages in southern Alabama and western Florida. Final Report for the U.S. Fish and Wildlife Service, Jacksonville, Florida. 61 pp.

  • Williams, J.D., M.L. Warren, Jr., K.S. Cummings, J.L. Harris, and R.J. Neves. 1993b. Conservation status of freshwater mussels of the United States and Canada. Fisheries 18(9): 6-22.

References for Watershed Distribution Map
  • U.S. Fish and Wildlife Service (USFWS). 2003. Candidate and listing priority assignment form: Fusconaia rotulata, Ptychobranchus jonesi, Fusconaia escambia, Lampsilis australis, Pleurobema strodeanum, Villosa choctawensis, Quincuncina burkei. U.S. Fish and Wildlife Service, Panama City Field Office, Panama. 20 pp.

  • Williams, J.D., A.E. Bogan, and J.T. Garner. 2008. Freshwater Mussels of Alabama & the Mobile Basin in Georgia, Mississippi & Tennessee. University of Alabama Press: Tuscaloosa, Alabama. 908 pp.

Use Guidelines & Citation

Use Guidelines and Citation

The Small Print: Trademark, Copyright, Citation Guidelines, Restrictions on Use, and Information Disclaimer.

Note: All species and ecological community data presented in NatureServe Explorer at http://explorer.natureserve.org were updated to be current with NatureServe's central databases as of March 2018.
Note: This report was printed on

Trademark Notice: "NatureServe", NatureServe Explorer, The NatureServe logo, and all other names of NatureServe programs referenced herein are trademarks of NatureServe. Any other product or company names mentioned herein are the trademarks of their respective owners.

Copyright Notice: Copyright © 2018 NatureServe, 4600 N. Fairfax Dr., 7th Floor, Arlington Virginia 22203, U.S.A. All Rights Reserved. Each document delivered from this server or web site may contain other proprietary notices and copyright information relating to that document. The following citation should be used in any published materials which reference the web site.

Citation for data on website including State Distribution, Watershed, and Reptile Range maps:
NatureServe. 2018. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available http://explorer.natureserve.org. (Accessed:

Citation for Bird Range Maps of North America:
Ridgely, R.S., T.F. Allnutt, T. Brooks, D.K. McNicol, D.W. Mehlman, B.E. Young, and J.R. Zook. 2003. Digital Distribution Maps of the Birds of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Bird Range Maps of North America:
"Data provided by NatureServe in collaboration with Robert Ridgely, James Zook, The Nature Conservancy - Migratory Bird Program, Conservation International - CABS, World Wildlife Fund - US, and Environment Canada - WILDSPACE."

Citation for Mammal Range Maps of North America:
Patterson, B.D., G. Ceballos, W. Sechrest, M.F. Tognelli, T. Brooks, L. Luna, P. Ortega, I. Salazar, and B.E. Young. 2003. Digital Distribution Maps of the Mammals of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Mammal Range Maps of North America:
"Data provided by NatureServe in collaboration with Bruce Patterson, Wes Sechrest, Marcelo Tognelli, Gerardo Ceballos, The Nature Conservancy-Migratory Bird Program, Conservation International-CABS, World Wildlife Fund-US, and Environment Canada-WILDSPACE."

Citation for Amphibian Range Maps of the Western Hemisphere:
IUCN, Conservation International, and NatureServe. 2004. Global Amphibian Assessment. IUCN, Conservation International, and NatureServe, Washington, DC and Arlington, Virginia, USA.

Acknowledgement Statement for Amphibian Range Maps of the Western Hemisphere:
"Data developed as part of the Global Amphibian Assessment and provided by IUCN-World Conservation Union, Conservation International and NatureServe."

NOTE: Full metadata for the Bird Range Maps of North America is available at:
http://www.natureserve.org/library/birdDistributionmapsmetadatav1.pdf.

Full metadata for the Mammal Range Maps of North America is available at:
http://www.natureserve.org/library/mammalsDistributionmetadatav1.pdf.

Restrictions on Use: Permission to use, copy and distribute documents delivered from this server is hereby granted under the following conditions:
  1. The above copyright notice must appear in all copies;
  2. Any use of the documents available from this server must be for informational purposes only and in no instance for commercial purposes;
  3. Some data may be downloaded to files and altered in format for analytical purposes, however the data should still be referenced using the citation above;
  4. No graphics available from this server can be used, copied or distributed separate from the accompanying text. Any rights not expressly granted herein are reserved by NatureServe. Nothing contained herein shall be construed as conferring by implication, estoppel, or otherwise any license or right under any trademark of NatureServe. No trademark owned by NatureServe may be used in advertising or promotion pertaining to the distribution of documents delivered from this server without specific advance permission from NatureServe. Except as expressly provided above, nothing contained herein shall be construed as conferring any license or right under any NatureServe copyright.
Information Warranty Disclaimer: All documents and related graphics provided by this server and any other documents which are referenced by or linked to this server are provided "as is" without warranty as to the currentness, completeness, or accuracy of any specific data. NatureServe hereby disclaims all warranties and conditions with regard to any documents provided by this server or any other documents which are referenced by or linked to this server, including but not limited to all implied warranties and conditions of merchantibility, fitness for a particular purpose, and non-infringement. NatureServe makes no representations about the suitability of the information delivered from this server or any other documents that are referenced to or linked to this server. In no event shall NatureServe be liable for any special, indirect, incidental, consequential damages, or for damages of any kind arising out of or in connection with the use or performance of information contained in any documents provided by this server or in any other documents which are referenced by or linked to this server, under any theory of liability used. NatureServe may update or make changes to the documents provided by this server at any time without notice; however, NatureServe makes no commitment to update the information contained herein. Since the data in the central databases are continually being updated, it is advisable to refresh data retrieved at least once a year after its receipt. The data provided is for planning, assessment, and informational purposes. Site specific projects or activities should be reviewed for potential environmental impacts with appropriate regulatory agencies. If ground-disturbing activities are proposed on a site, the appropriate state natural heritage program(s) or conservation data center can be contacted for a site-specific review of the project area (see Visit Local Programs).

Feedback Request: NatureServe encourages users to let us know of any errors or significant omissions that you find in the data through (see Contact Us). Your comments will be very valuable in improving the overall quality of our databases for the benefit of all users.